The invention discloses the use of a compound of formula (I), wherein R.sup.1, R.sup.2, R.sup.3, and R.sup.4 each independently represents: hydrogen; halo; hydroxy; (C.sub.1-C.sub.6) alkyl optionally substituted by hydroxy or (C.sub.1-C.sub.4) alkoxy; (C.sub.1-C.sub.6) haloalkyl; (C.sub.1-C.sub.6) alkoxy; and (C.sub.1-C.sub.6) haloalkoxy; for the preparation of a medicament for the prevention and/or treatment of diseases resulting from opening of the MPTP which are characterized by degenerative tissue damages, in particular, diabetes and diabetic complications, neurological diseases and stroke, heart infarction, inherited dystrophies and hepatitis, more particularly, diabetic vascular diseases, such as diabetic retinopathy, and neurodegenerative disorders, such as multiple sclerosis. Further objects are a group of selected individual compounds of formula (I) for use as medicaments and a further group of selected individual compounds of formula (I) as novel compounds. ##STR00001##